Sedova, V. F.; Mustafina, T. Yu.; Krivopalov, V. P.; Mamaev, V. P. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , p. 91 - 94 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , vol. 19, # 1 p. 102 - 106